A communication system is a facility which enables communication between two or more entities such as user terminal equipment and/or network entities and other nodes associated with a communication system. The communication may comprise, for example, communication of voice, electronic mail (email), text messages, data, multimedia and so on.
The communication may be provided by a fixed line and/or wireless communication interface. A feature of wireless communication systems is that they provide mobility for the users thereof. An example of communication systems providing wireless communication are public land mobile networks (PLMN). An example of the fixed line system is a public switched telephone network (PSTN).
A communication system typically operates in accordance with a given standard or specification which sets out what the various elements of a system are permitted to do and how that should be achieved. For example, the standard or specification may define if the user, or more precisely user equipment, is provided with a circuit switched server or a packet switched server or both. Communication protocols and/or parameters which should be used for the connection also typically defined. For example, the manner in which communication should be implemented between the user equipment and the elements of the communication networks is typically based on a predefined communication protocol. In other words, a specific set of “rules” on which the communication can be based needs to be defined to enable the user equipment to communicate via the communication system.
So called third generation communication systems are being introduced. These so called third generation systems use code division multiple access techniques. One example of such a third generation communication system is the cdma2000 system (Code Division Multiple Access, version 2000 (including data)).
Current cdma2000 networks support three modes of service, simple IP (internet protocol) v4, simple IPv6 and mobile IPv4. The next release of cdma2000 packet data network (see proposed standard TIA 835D) plans to have mobile IPv6 as a fourth mode of service for the mobile station. The requirements for IPv6 mobility in cdma2000 have required that the dynamic assignment of home address and home agent for a mobile station be possible.
A mobile station is identified by a unique home address through which it is always reachable. A home agent is a router that serves mobile stations that belong to the home network that the home agent serves.
The current mobile IPv6 specification does define a mechanism for dynamic home agent assignment. However, this mechanism is undesirable in that it is not secure. In practice, home agents in cellular operator networks are not likely to respond to unauthenticated requests with a list of home agents. Furthermore, no mechanism for dynamic assignment of home address is provided in the current mobile IPv6 specification.
It is an aim of embodiments of the present invention to address or at least mitigate the above described problems.